1. Field of the invention
The present disclosure relates to a motor.
2. Description of Related Art
In general, a brushless motor can generate an electric power by an electric interaction between a stator wound with a coil and a rotor having a magnet centrally arranged at the stator. At this time, the magnet mounted on the motor may be installed at a surface of a rotor core or may be installed at a pocket inside the rotor core.
In a case a magnet is installed on a surface of a dual rotor core, the magnet is bonded to the surface of the rotor core using an adhesive, where the magnet is generally adhered to the surface of the rotor core by arranging a plurality of magnet members each having a same size.
A rotor, in which a rotation shaft is press-fitted into a center of the rotor core, may have a guide rib on the surface of the rotor core for restricting an adhesion position of the magnet as the rotor core has an allowable thickness, or may allow the magnet to be adhered/fixed into a groove by forming the groove of a predetermined size.
However, in a case a tube-type rotor required with a space at a center of the rotor core for changing a rotational power of the rotor to a linear reciprocal motion, the rotor core generally has a thin thickness like a pipe, and is centrally disposed with a space unit, making it difficult to form a guide rib or a magnet accommodation groove for attaching the magnet, and therefore a magnet is attached on to the surface of a smooth tube type rotor core.
In a case the magnet attached on to the surface of the smooth tube type rotor core, it is difficult to maintain position accuracy between magnets due to difficulty in adhering/fixing the magnets each at a predetermined gap. Another disadvantage is that separate disengagement prevention means must be provided to inhibit the magnets from being disengaged at a high speed rotation region because the magnets are attached on the smooth tube type rotor core.
In case of disengagement prevention coating formed by injection molding using a large quantity of resin, resin cannot be generally formed with a thick thickness for maintaining the motor performance more than a predetermined level to make it difficult to obtain a sufficient magnet disengagement prevention effect.